A side light-emitting device or a surface mount light-emitting device including a light-emitting element formed, e.g., with a semiconductor is compact and power-efficient, and emits light having a vivid color.
Such side light-emitting devices, surface mount light-emitting devices and the like encompass a type of light-emitting device that includes a protection element formed, e.g., with a Zener diode, so as to improve its tolerance to (i) a reverse voltage and (ii) a serge voltage caused, e.g., by static electricity, both applied to its light-emitting element. The protection element is electrically connected to the light-emitting element within the light-emitting device.
FIG. 9 is a cross-sectional view illustrating a light-emitting device including a conventional protection element (see Patent Literature 1). The light-emitting device 100 includes: a light-emitting element 102; and a protection element 101 formed with a Zener diode. The protection element 101 is electrically connected to the light-emitting element 102 in parallel. A reverse voltage applied to the light-emitting element 102 causes a current to flow through the protection element 101. This allows for protection of the light-emitting element 102. Further, application of an overvoltage, higher than a certain voltage, to the light-emitting element 102 causes a voltage applied to the protection element 101 to exceed the Zener voltage value. This in turn causes a current to flow through the protection element 101 and thus protects the light-emitting element 102.
However, the above arrangement poses the following problem: The inclusion of the protection element 101 in the light-emitting device 100 causes light from the light-emitting element 102 to be absorbed or blocked by the protection element 101. This significantly reduces an amount of light emitted from the light-emitting device 100 to the outside.
To solve this problem, Patent Literature 1 discloses an arrangement in which (i) a recess is formed below the protection element 101 illustrated in FIG. 9, and the protection element 101 is mounted in the recess so as to be positioned lower than the light-emitting element 102, or (ii) a spacer is provided below the light-emitting element 102 so that the light-emitting element 102 is positioned higher than the protection element 101. This arrangement reduces an influence of the protection element 101 absorbing or blocking light.
FIG. 10 is a perspective view illustrating a light-emitting device including a conventional protection element (see Patent Literature 2). The light-emitting device 200 includes an insulating substrate 203; light-emitting elements 202 mounted on an upper surface of the insulating substrate 203; and protection elements 201. The insulating substrate 203 is depressed, along a direction from its upper surface toward its bottom surface, in a region of its upper surface, the region having no light-emitting element 202 provided therein, whereby a concave opening section 204 is formed. The protection elements 201 are contained in the concave opening section 204. In addition, the concave opening section 204 is sealed with a light-reflecting member 205 capable of reflecting light from the light-emitting elements 202. Further, the light-reflecting member 205 and the light-emitting elements 202 are covered with a light-transmitting member 206 capable of transmitting light from the light-emitting elements 202.
The light-reflecting member 205 reflects light from the light-emitting elements 202 toward an upper surface of the light-emitting device 200. This prevents such light from being absorbed or blocked by the protection elements 201.